Have look into the blog about Leaflet Js hope this will be helpful for you.
I have the same problem and still could not solve it. Did you apply the suggestion provided by Javith?
For anyone who may find this post here is what I did to solve this issue.
The solution doesn’t account for completely dynamic images because it requires all images to have their own line-item in the marker list.
I ended up adding a line item to the marker list for every Image that we required to be on our map. Each line item’s visualization was set to a static image. Then the datasource on each Marker list item was set to filter by xpath based off of an enumeration value that corresponded to to the specific image on the the Marker list item.
This solution allowed us to set the marker image for each data item to show up on the map with. However, if we ever need to add any new images it requires that we add a value to the enumeration, add a new image to an image collection in Studio Pro, and add a new Marker list item to the map widget.
I still wish that there was an easy way to pull a dynamic image to display on the map as it would be much more maintainable and make the widget more capable.